Control for electron tubes



I Nov. 15, 1932. 1 LE VAN 1,887,766

' CONTROL FOR ELECTRON TUBES Filed Oct 12. 1 929 2 Sheets-Sheet 1 1 U T mwm Nov. 15, 1932.

J. D. LE VAN 1,887,766

CONTROL FOR ELECTRON TUBES Filed Oct. 12. 1929 2 Sheets- Sheet 2 Ely-.6 5 E3 4 34* 6 61W 51 V ur/l'qye 1 0 f qye BMW:

. :6 main 7 electrodes.

Patented Nov. 15,

. U E A s PATENT OFFICE .rAn-s 11.132. mm, or KILWAUKEE, wrsconsm, Assrenoa 'ro .ourmn aumnn, mo, or mwAum, wrsoonsm, A coaromrron or DELAWARE com nor. I'OB'ELECTRON roams A umm filed cam: 12, 1929. Serial 110.309.1421.

This invention relatesto control of electrontubes and is especially applicable to tubes of the t pe disclosed in my copending application erial 319,918, filed Nov. 16, 1928,

. 5' An object of the invention is the control of mat di erent moments of the positive half cycle depending upon the moment at which the instantaneous voltage on the grid reaches a certain valuerelativeto the voltage between the main electrodes;

15 "Electron tubes of the gaseous'type in which the discharge to the anode is controlled by an auxiliary electrode or grid are well known in the art. In the past the anode current was controlled so as to increase or decrease in re- 20 spouse to" and directly in accordance with an increase or decrease of a positive potential im 'ressed upon the grid. A negative-potentia impressed upon the grid always prevented the start of the discharge between the I have disclosed in my aforementioned copending application a tube in which the main discharge is'controlled by impressing upon the grid a variable negative potential so that no substantial current flows to the anode "while'thegrid potential is of a relatively lownegative value, but that the discharge to the anode starts. suddenly when the negative potential of the grid reaches a certain higher value-which value is dependent upon the design of the tube and the instantaneous value of the potential between vrnain electrodes. 1 a

The accompanying drawings illustrate severalembodiments of my invention.

Fig. 1 illustrates the control of the main discharge by applying an adjustable direct current potential to the grid.

Fig. 2 shows diagrammatically the voltage and current relations in the tube.

Fig. 3 shows another embodiment of my invention wherein the moment of application of a high negative potential to the grid is.

varied relative to the'time phase of the alter= natmg voltage impressed upon the niain electrodes. T

, Fig. 4 shows the operation of the system disclosed in Fig. 3.

Fig. 5 shows still another system in which the grid potential is alternating and the time phase of said grid potential is varied relative to the time phase of the potential between the main electrodes.

"Fig. 6v shows diagranmiatically the current and voltage relations of the system illustrated in Fig. 5. J Referring to Fig. 1 the numeral 1 denotes a gaseous discharge tube having an anode 2, a. grid 3, a cathode 4 and an auxiliary electrode 6, the purpose of which is to maintain a discharge between itself and the cathode 4, which discharge is supplied with current by the battery 7, the current being regulable through a resistance 8.

A source of alternating current 9 has one terminal connected with the. anode 2 b means of conductor 10, while its other term1- nal is connected by means of conductor 11 to translating device 12, which in turn is connected by conductor 13 and the leading-in wire 5 to cathode 4;. A battery 14 which is paralleled by a potentiometer resistance 15 has its negative pole connected to the grid 3 and its positive pole to cathode 4.

It now* an alternating current of a certain potential is applied between the cathode 4 and the-anode 2 while the grid potential is zero, current will start during the half cycle when the anode 2 is positive at the moment when the alternating voltage has reached a value which is de endent upon the characteristic of the tube. uch current will then continueto flow until the positive voltage of the anode 2 has again decreased .to substantially zero value. During the next half cycle the anode 2 is negative'and therefore no current can flow through the tube, while during the third half cycle the polarity of the anode is again spect to the cathode by adjustment of the potentiometer 15, thepositive voltage which is required on the anode 2 to start the disso that the moment at which the current starts to flow during the positive half cycle can beadvanced at will. It is thus possible, b var ing the negative grid potential, to regu ate t e total amount of energy which passes throu h the tube during a half cycle and" thus also t e total amount of energy which passes through the translating device 12.

Figure 2 illustrates the operation of the device. The curve S represents one cycle of the alternating potential which is impressed between the anode and the cathode. .It has been observed that the glow potential of'the tube varies somewhat with the potential S. If a potential vEg, which is negative with respect to the cathode, is impressed upon the grid of such a value that for any given instantaneous potential between the main electrodes, the instantaneous voltage between 2 and '3 is less than the low voltage, no glow discharge is initiated Eetween the grid and the anode and thus no current starts to flow between the main electrodes. If a higher negative potential Eg is impressed upon the grid of such avalue that the maximum resultant voltage between 2 and 3 is just equal to the glow voltage of the tube at themoment when the main voltage attains its maximum instantaneous value, current flow between the cathode and anode is initiated at the moment B resulting in a current wave shown approximately by the curve BCF. If the grid voltage is still further increased to the valve Eg so that it is I equal to the golw voltage of the tube for substantially zero main voltage, the flow of current between the main electrode is initiated at the moment A resulting in a current represented by thecurve ADF.

In Fig. 3, 20 is the electron discharge tube having the cathode 21 and anode 22. The

grid 23 and the auxiliary electrode 24 which is sup lied with current from the battery 25 and t e characteristics of the tube are the same as those of the tube 1 shown in and described in connection with Fig. 1. 26 is a source of alternating current energy, while27 is a translating device the current of which is to be controll d by grid 23. A synchronous motor 28 is suplied with energy from the source 26 so that its armature rotates in synchronism with the current supplied to the tube. The motor drives a rotating commutator 29 which has a continuous segment-29a and connected therewith an interrupted segment 30 making contact with'the brushes 31 and 32 respectively.

The brush 32 may be revolved so that themoment at which it makes contact with segment 30 during each revolution may be varied. Batteries 34 and supply the necessary potentials tothe grid 23. A resistance 33 is connected across the brushes 31 and 32.

Referring to F? gs. 3 and 4 the device operates in the following manner:

E is the alternating potential impressed tween brush 32 and se between the cathode 21 and anode 22 and Eg is the minimum negative grid potential supplie'd by the battery 34 which is assumed not to be suflicient to starta dischar e between main electrodes, the rotation o the com mutator causes at the moment t contact be- The resistance 33 is inserted to prevent a short circuit of. the battery 35 at'the time when the brush 32 makes contact with segment 30.

The system illustrated in Fig. 5 employs an electron tube 40 which may be of the same construction as the tube illustrated in Fi 1.

L, L2 andL3 are power lines suppl ing t ree phase alternatin current. The W 40 and the translating lator 47 having ing 48 and t e rotatable secondary single phase winding 49 is also connected to lines L, L2 and L3. A rectifier element 50 of any well known type is inserted in the connection between the secondari; winding 49 and the grid 43, so that only t pass to the grid 43. The battery 51 which is 'connected in series with the limiting resistor 52 between the cathode 41 and the 'd 43 serves to maintain the grid 43 at the minimum negative potential at which no discharge can take placebetweenthe main electrodes. The alternating voltage induced in the secondary. winding 49, which is impressed upon the grid of the tubemay be varied in phase relative to the time phase of the voltage impressed upon the mam electrodes.

Fig.v 6 shows the operation of the system. E is the voltage impressed upon the main electrodes of the tube while E9 is'thevoltage impressed ufion the grid of the tube'by the batte 51. g is the alternatin voltage impresse upon the id of the tuie for a certain position of t e induction regulator secondary winding. As lon as the voltage Eg' is-negative and below t e glow voltage of the tube during that half cycle when the voltage E, is positive, no discharge can take place between themain electrodes. At the moment t, the sum of the voltage Eg and the main voltage E is equal to the glow voltage of the tube and a discharge takes place between the main electrodes. The current e negative half waves of the currentinduced in the winding 49 can out 30 and thus the evice 46 are connected be tween lines L2 and L3. An induction reguthe polyphase primary windseamen during the remainderof the half cycle is re 'rw ented by the curve IL. If now the secon ary winding 49 is rotated so that the voltage impressed u n the grid is advanced in phase relative to t e main voltage" as represented by curve E9 the glow voltage is reached at the earlier moment t,- of thehalf cycle. Ignition takes place at this-earlier moment, and the current which asses between the main electrodes duringtiie corresponding half cycle is representedby the curve IL. While I have shown a number of embodiments of my invention for the purpose of describing the same, it' will'be apparent that many other variations of the gstem are fose scope o the an ionizable gas and having associated wit its anode a grid efl'ecti've when supplied with a relatively low potential negative with'respect to the cathode to prevent discharge between the main electrodes and to aid initiation of such discharge by producing a glow discharge between the grid and anode when said negative grid potential has a relatively high value.

2. An electron discharge tube containing an ionizable gas and having associated with its anode a grid supplied with a variable potential ne tive .withrespect to the cathode and effective to start a discharge between the main electrodes by producing a glow discharge between the grid and anode when the potential betweemthe grid and the anode attains a given value.

3. Anelectron discharge tube containing an ionizable gas and having associated with its anode a grid supplied with a relatively low potential negative with respect to the cathode. to prevent discharge between the L .main electrodes and means to temporarily increase said negative grid potential to produce a glow discharge between the grid and anode and to thereby initiate said first-mentioned discharge. y I l 4. An electron discharge-tube-containing an ionizable gas and having associated, with its anode a grid supplied with a relatively low potential negative with respect to the cathode to inhibit discharge between the'main electrodes and means to increase said negative potential at a given moment to produce a glow discharge between the grid and anode and to thereby initiate said first-mentioned ionizable gas and havin associated with its anode a grid efiective w en sup lied with a variable otential negative'witli respect to the catho e, to. produce a glow discharge between the grid and anode, for reducin the starting potential of the tube in accor ance with said grid potential. I v

6. An electron discharge tube supplied with an alternatin potential, containing an ionizablegas and having associated with its anode a grid efiectivewhen supplied with a variable potential negative with respect to the cathode, to produce a glow dischar the grid and anode, for reduc'ng t e startln potential of the tube in accor ance with sai grid potential.

7; An electron discharge tube supplled with an alternating potential containing an ionizable gas-and havin associated-with its anode a grid efiective w en supplied with a variable unidirectional potential negative with respect to-the cathode, to produce a glow discharge between the grid' and anode, for reducing the starting potential of the tube in accordance with said grid otential.

8s The method of contro ling the operation of an electron discharge tube containing an ionizable as and havin associated with its anode a grid, which consists in supplying said grid with a potential negative with respect to 9 the cathode, capable of producing a glow discharge between the grid and anode and therebetween by reduce the potential required for initiation of discharge.

9. The method of controlling the discharge of an electron tube having a varying potential impressed between its anode and cathode, containing an ionizable gas and a gridassociated with its anode, which consists in supplying said grid with a potential negative with respect to the cathode, capable of producing a, glow discharge between the grid and anode'to reduce the starting potential and varying said grid potential to thereby control said starting potential.

10. The method of controlling the discharge of an electron-tube which is supplied from an' alternating source, containing an ionizable gas and a grid associated -'with its anode, which consists in supplying said grid with a potential ne ative with respect to the cathode, capable o? producing a glow discharge between the grid and anode to reduce the starting potential and varying said grid potential, to thereby control the instantaneous discharge starting voltage of alternative half cycles.

- 11. The method of controlling the discharge of an electron tube which is supplied from an alternating source, containing an ionizable gas and a grid associated with its anode, which consists in supplying said'grid with a constant potential negative with respect to the cathode to reduce the starting potential and regulating said grid potential to thereby produce a glow discharge between I the'grid and-anode and control the instantaneous discharge starting voltage of alternative half cycles.

a 12. The method 1 of controlling the discharge of an electron tube which is supplied from an alternating source, containin an ionizable gas and a grid associated wit its anode, which consists in supplyirig said grid with a low potential ne t ive with respect to the cathode to inhibit ischarge between the main electrodes and raising this negative potential at a desired moment to a higher value which produces a glow discharge between the l grid and anode to thereby initiate said discharge at that moment of the alternating cycle. Y

In witness whereof, I have hereunto subscribed my name.

' JAMES D. LE VAN. 

